Impedimetric Study of Aptamer Immobilized 4-Aminophenylacetic acid Modified Carbon Electrode for Glyphosate Detection

Abstract

The development of aptasensor to detect hazardous herbicide, glyphosate (GLY), is proposed in this study. An amino-labeled aptamer was immobilized onto the carboxylic group of 4-aminophenylacetic acid (CMA)- modified screen-printed carbon electrode (SPCE) as a sensing strategy. The alterations of electrode surface were characterized by scanning electron microscopy (SEM), Fourier-transformed infrared (FTIR) spectroscopy, Raman spectroscopy, contact angle analysis, and electrochemical studies using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Furthermore, the analytical performances were mainly investigated by EIS study. The proposed aptasensor demonstrated a good linear response ranging from 10.0 nM to 10.0 µM with a correlation coefficient square (R2) of 0.9986. A calculated limit of detection (LOD) of 0.0515 µM and sensitivity of 0.564 Ω µM-1cm-2 were obtained. A good selectivity against various interferences including glycine, captan, diquat, and paraquat was also achieved. Moreover, the recovery rates in spiked tap water, orange juice, and strawberries showed satisfactory outcomes in the range of 87.8 to 120.3 %. Hence, the proposed aptasensor could serve as a promising technique for glyphosate detection in order to prevent its excessive accumulation in environments and commodities, thus ensuring safety for human livelihood and healthiness.